1. Field of the Invention
The present invention relates to a capacitor in a semiconductor device and a method for fabricating the same, more particularly to a capacitor in a semiconductor device and a method for fabricating the same, in which an Ru (Ruthenium) metal is employed as a lower electrode and an upper electrode in a metal-nonconductor-metal structure.
2. Description of the Prior Art
As generally known in the art, a capacitor which is capable of storing much electrical charge in a small area along with a high integration of a semiconductor device is required. Therefore, a capacitor with a metal-nonconductor-silicon structure employing TiON (xcex5r=xe2x88x9250) which has a high dielectric ratio, is used for a DRAM which has a capacity above 256 Mb, instead of a conventional NO film.
However, the capacitor with the metal-nonconductor-silicon structure comes to a limitation in fabricating a capacitor having a high capacity, because SiO2 is formed at an interface between a dielectric TiON and a polysilicon layer which is a storage node.
Accordingly, a capacitor with a metal-nonconductor-metal structure is employed in a DRAM of a giga-bit level. In this case, as polysilicon is employed as a plug, a barrier/plug with a TiN2/TiSi2/Si structure is employed in spite of some problems in the fabricating process.
However, as the oxidation resistant property of a TiN/TiSi2 layer is not adequate, a barrier layer is oxidized due to oxygen which remains in a lower electrode and flows in from outside in following processes, which improves heat treatment of the lower electrode and crystallization of the dielectric and leakage currents characteristics.
Accordingly, the present invention has been made to solve the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide a capacitor in a semiconductor device and fabricating method for the same, which is capable of improving electrical characteristics of a capacitor by employing a dual dielectric composed of Y2O3/TiON.
In order to accomplish this object, there is provided a capacitor in a semiconductor device comprising: a semiconductor substrate, a first Ru film formed on the semiconductor substrate, a Y2O3 film formed on the first Ru film, a TiON film formed on the Y2O3 film; and a second Ru film formed on the TiON film.
Also, according to another aspect of the present invention, there is provided a method for fabricating a capacitor in a semiconductor device comprising the steps of: providing a semiconductor substrate, forming a first Ru film on the semiconductor substrate, forming a Y2O3 film on the first Ru film, forming a TiON film on the Y2O3 film, and forming a second Ru film on the TiON film.